Re: [Xen-devel] [PATCH] xen/arm: Update VTCR to use region size of 2^40 bytes instead of 2^39

[Tim Deegan <tim@xxxxxxx>]

At 13:06 +0100 on 06 Jun (1370524015), Julien Grall wrote:
> According to the ARM manual, T0SZ is a 4-bit signed integer.
> The current value of T0SZ = b1000 which is equal to -7. This is result

Really?  By my count, 4-bit -7 is b1001 and b1000 is indeed -8.

> to a size of 2^39 bytes instead of the desired value 2^40.
> 
> Signed-off-by: Julien Grall <julien.grall@xxxxxxxxxx>
> ---
>  xen/arch/arm/mm.c |    4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/xen/arch/arm/mm.c b/xen/arch/arm/mm.c
> index d1290cd..7d4e186 100644
> --- a/xen/arch/arm/mm.c
> +++ b/xen/arch/arm/mm.c
> @@ -315,9 +315,9 @@ void __cpuinit setup_virt_paging(void)
>      /* Setup Stage 2 address translation */
>      /* SH0=00, ORGN0=IRGN0=01
>       * SL0=01 (Level-1)
> -     * T0SZ=(1)1000 = -8 (40 bit physical addresses)
> +     * T0SZ=(1)1111 = -8 (40 bit physical addresses)

That's certainly wrong: b1111 must be -1.

Tim.

>       */
> -    WRITE_SYSREG32(0x80002558, VTCR_EL2); isb();
> +    WRITE_SYSREG32(0x8000255f, VTCR_EL2); isb();
>  }
>  
>  /* This needs to be a macro to stop the compiler spilling to the stack
> -- 
> 1.7.10.4
> 
> 
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